The invention relates to a food product comprising an aqueous phase and gas bubbles, and to a process for the preparation thereof. The invention especially relates to emulsions of an aqueous phase and a fatty phase, which emulsion additionally comprises gas bubbles.
Food products in the form of emulsions are known. Examples are emulsions of a fatty phase and an aqueous phase, such as margarines (water in oil emulsions), fresh cheese (oil in water emulsion) and dressings (oil in water emulsion).
The physical stability of these products is quite important.
For example liquid or pourable emulsions may be relatively unstable in that water droplets which are part of the dispersed aqueous phase can sediment to the bottom of the emulsion. In the current application where reference is made to a xe2x80x9cstablexe2x80x9d system, avoiding the phenomenon of sedimentation of one phase is referred to. Sedimentation is seen in products comprising a fat phase and a dispersed aqueous phase, whereby water droplets sink to the bottom of the system, where a water droplet layer is formed. Simultaneously an oil layer may be formed on top of the product, although usually most oil will still be present in the emulsion layer. Under extreme circumstances sedimentation may lead to the formation of a separated aqueous phase and a separated oil phase.
The formation of an oil layer on top of an emulsion is referred to as oil exudation. Stable products show less than 20 vol % oil exudation, more preferred less than 10 vol % after storage for 4 weeks at a temperature of 5xc2x0 C.
FR-A-7040472 discloses that the separation of a liquid margarine into two phases can also be at least partly overcome by incorporation of gas bubbles into said margarine. The size of the gas bubble is preferably between 1 and 25 xcexcm, most preferred 2-10 xcexcm. In this product gas is present in the oil phase.
WO 94/12063 discloses the use of gas cells in food products. Food products such as low fat spreads are disclosed, said products comprising gas cells and having a thermodynamic stability in excess of 2 weeks. More than 90% by number of the gas cells in said products have an average D3,2 particle size of less than 20 xcexcm, most preferred 0.5 to 3 xcexcm. The gas cells are prepared by application of high shear to the product or a pre mix.
It is furthermore known that the separation of a liquid margarine into two layers can be overcome at least partly by selection of a specific hardstock fat composition.
Although some of the above disclosed products show some improvement in stability against phase separation the above described methods and products often do not give satisfactory results.
Several problems are encountered if the prior art products are used.
Firstly the products disclosed in the cited documents do not show the required stability over time and the gas bubbles in these products are slowly dissolving over time in the product, instead of remaining in a dispersed state. Secondly the disclosed gas bubbles do not show the desired stability to survive processing conditions, especially when shear is applied at one or more stages.
Furthermore hardstock fat compositions that are used to improve stability of pourable water in oil emulsions such as liquid margarines, lead to products with increased viscosity. This increased viscosity can be undesirable for pourable products. Therefore avoiding the use of hardstock fat composition is desired.
Emulsions of water in oil, like margarine or other fat continuous emulsions are used as frying medium for the frying of food stuff.
It is known that during frying evaporation of the aqueous phase of fat and water containing products may cause severe spattering. Spattering of a water in oil emulsion is believed to be caused by the superheating of water droplets. At a certain point after heating said water droplets explosively evaporate, whereby oil can be spread all over the surroundings of a frying pan in which the emulsion is heated. This is not only unpleasant and needs cleaning, more significantly it may cause danger to the person who intends to fry foodstuff in the heated emulsion.
In the prior art, products are disclosed that show reduced spattering. For example additives like salt, emulsifiers or specific proteins can serve to reduce spattering.
Furthermore EP-A-285,198 discloses an edible plastified product comprising a continuous fat phase and a finely dispersed helium gas phase. The presence of a dispersed gas phase in these products is said to be beneficial for the spattering behavior of these products in frying, especially if the products comprise a dispersed phase.
Several products are linked to the use of the products according to EP-A-285,198. Firstly the gas bubbles in these products also slowly dissolved in the plastified food product and secondly they do not survive processing to a desired extent. Furthermore these products show the disadvantage that only helium can be applied as gas.
Furthermore JP-A-54110210 discloses a method to reduce spattering whereby a gaseous CO2 generating substance is added to a phospholipid containing oil. Upon heating, said substance releases CO2, whereby the spattering of oil can be reduced.
It has now been found that the above problems can all be solved by a food product comprising an aqueous phase comprising dispersed gas bubbles, wherein said gas bubbles are substantially dispersed in the aqueous phase, wherein said gas bubbles have a mean diameter size distribution with a maximum below 10 xcexcm and wherein said aqueous phase comprises a compound capable of forming at least a partial coating around said gas bubbles.
Accordingly the present invention relates to a food product comprising an aqueous phase and gas bubbles, whereby said gas bubbles are substantially dispersed in the aqueous phase, and whereby said bubbles have a mean diameter size distribution with a maximum below 10 xcexcm and in that said aqueous phase comprises a compound capable of forming at least a partial coating around said gas bubbles.
The invention also relates to a process for the preparation of these food products.